Metals and Non-Metals — Science STD 10 — Question

An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.

What is meant by an addition reaction? Give an example (with equation) of an addition reaction of an alkene.

Write the balanced chemical equations for the following reaction.
Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogencarbonate.

What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?

What happens when a cold and concentrated solution of sodium chloride reacts with ammonia and carbon dioxide? Write the chemical equation of the reaction which takes place.

Can the following groups of elements be classified as Dobereiner's triad?

1. Na, Si, Cl.
2. Be, Mg, Ca.

Atomic mass of Be 9; Na 23; Mg 24; Si 28; Cl 35; Ca 40. Explain by giving reason.

Given alongside is a part of the periodic table. As we move vertically downward from Li to Fr:

1. What happens to the size of atoms?
2. What happens to their metallic character?

In nature, metal A is found in a free state while metal B is found in the form of its compounds. Which of these two will be nearer to the top of the activity series of metals?

What is a redox reaction? Explain with an example.

State two uses of ethanol (other than as a fuel).